Non Fiat Advice - Bearing Noise

[SB1500]

Asking for a friend with a VW 1.9 TDI, he has a bearing noise that increases with the speed of the car. He replaced the bearings on all wheels. It's still happening, but it disappears when the clutch is pressed in...

Any ideas on what to investigate regarding this?

 

[s130]

Possibly:

1) the clutch trust bearing is dragging on the pressure plate release surface but when the clutch is pressed the bearing is being loaded and the noise is dampened down. If this is the case then gently playing with the clutch pedal one may be able to "modulate" the intensity of the noise

2) gearbox input drive or lay shaft bearing. If the bearing noise changes with engine speed in neutral then it is most probably a bearing on the input drive shaft. If the bearing noise changes with gear selected/road speed then most probably a bearing on the lay shaft

 

[DaveMcT]

It could be the clutch but gearbox input shaft bearing is more likely. The rattle will be there in neutral but stops when you put the clutch down. It will also be there as you slow down in gear or coasting in neutral and again will stop when you put the clutch down.

The clutch release bearing damps the noise but also helps to support the wobbly shaft so that also reduces the noise.

It might be fixable with new input shaft bearings. But who knows if that's within normal "mechanicking". He is probably looking at a reconditioned gearbox. Don't forget to replace the needle roller nose bearing in the end of the crankshaft.

 

[Pugglt Auld Jock]

OP says it increases with road speed doesn't he? So I think less likely to be 1st motion shaft or something before that like clutch release bearing? Final drive, laygear cluster and 3rd motion shaft all rotate at speed relative to wheel rpm. Puzzles me a little that all wheel bearings were replaced. Although if the noise increases with road speed, I can understand that a wheel bearing might be suspected, although weaving the car will usually isolate a weel bearing for you? - but all 4? Then again "disappears when the clutch is pushed in, weird given the other symptoms? I think before chucking any more money at it he should let a VAG specialist or gearbox specialist listen to it - might be that several bearings are knackered (Who knows, 1st motion shaft and pinion bearing for example. If it's had a bearing going for a wee while bits from it might have "migrated" to other bearings and done them in too!)

 

[SB1500]

Some more info; Once the car is up around 60mph there is a hum. When continuously going at this speed with the same rev on the engine but put the clutch in it disappears

 

[DaveMcT]

If it is gearbox it has to be first motion bearings as that's the only one affected by clutch. It could also be a clutch issue - release bearing dragging or a fault with pressure plate fingers.

You need to see if the noise comes and goes in neutral. Park the car, run the engine on tickover and listen (from under the bonnet) to see if noise comes and goes. If there is no noise then you are looking at the wheels end of the transmission but who knows why the clutch would affect that.

 

[Pugglt Auld Jock]

The suspense is killing me! Please do let us know how this one pans out won't you?

 

[SB1500]

I will keep you all updated.

This Bora also had the back axel fall through on it and needs new brake lines etc. There is possible discussion of a new car too..

 

[DaveMcT]

This has to be a bargain, even with pallet delivery costs.

eBay item number 362528546595

And these
https://www.ebay.co.uk/sch/i.html?_...ra+gearbox.TRS0&_nkw=VW+Bora+gearbox&_sacat=0

 

[SB1500]

The Bora is still here but not being fixed anymore.

He’s looking at a 2015 2.2 automatic diesel Mazda 6 sport now. Night and day upgrade I’d imagine!